Thermal polymerization of dicyclopentadiene

ABSTRACT

The specification discloses a method for making DCPD based resins that have relatively narrow molecular weight distributions. The method comprises thermally polymerizing dicyclopentadiene monomer in the presence of one or more strong acids, preferably with an olefinic modifier, to provide a dicyclopentadiene oligomer. Optionally, an organic sulfur species can also be used to further effect molecular weight control. For end-use performance in inks, adhesives, coatings and other related areas, the invention provides dicyclopentadiene oligomer resins having weight average molecular weights less than 1000 and relatively narrow molecular weight distributions, as measured by a polydispersity index, of less than about 2.3. Among the strong acids that are effective for controlling molecular weight, hypophosphorous acid is preferred because it gives light colored resins.

This is a continuation of application Ser. No. 08/353,729, filed on Dec.12, 1994, abandoned, which is a division of application Serial No.08/185,057, filed on Jan. 24, 1994, now U.S. Pat. No. 5,410,004, whichissued Apr. 25, 1995.

FIELD OF THE INVENTION

This invention relates to methods for controlling the molecular weight,molecular weight distribution and color of resins prepared fromdicyclopentadiene (DCPD) monomer by thermal polymerization processes, toresins produced by such methods and products including resins.

BACKGROUND OF THE INVENTION

Adhesives, inks and coatings are typically blended formulationsconsisting of high molecular weight polymers, resins, oils, waxes,pigments, solvents and other additives. In all of these formulations, itis well documented that the resins are major and crucial componentsneeded to impart the formulation rheology and end-use performancecharacteristics. It is also well documented that resin molecular weightand molecular weight distribution, taken in combination with a resin'ssolubility characteristics, affect resin performance and the propertiesof products incorporating the resin. In general, in accordance with wellaccepted theory, resins having lower molecular weights have bettercompatibility and solubility properties relative to those having highermolecular weights for use in the above and other formulations. It is forthese reasons that resins containing high molecular weight fractions donot work well in adhesive formulations. Also, the resins used for inkpigment flushing give better pigment wetting and therefore betterflushing performance if they have a low average molecular weight and arefree of a high molecular weight fraction. Thus, control of molecularweight and molecular weight distribution is important in the creation ofhigh utility resin products.

It is to be noted that a reference to the molecular weight of a resin orpolymer, in reality, is a reference to an average molecular weightbecause, with few exceptions, polymers are complex mixtures of moleculeshaving different molecular weights. The mixture of different molecularweights is called polydispersity. The reason for polydispersity relatesto the statistical variations inherent to polymerization processes andthe purity of raw materials. The following mathematical expressionsdefine the three different molecular weight averages that are routinelyused to characterize resins and polymers:

    M.sub.n =number average molecular weight=ΣN.sub.i W.sub.i /ΣN.sub.i,

    M.sub.w =weight average molecular weight=ΣN.sub.1 W.sub.i.sup.2 /ΣN.sub.i W.sub.i,

    M.sub.2 =z average molecular weight=ΣN.sub.1 W.sub.i.sup.3 /ΣN.sub.i W.sub.i.sup.2,

where N_(i) is the number or moles of a material having a molecularweight of W_(i).

The ratio of M_(w) /M_(n), defined as the polydispersity index (PDI), isa measure of the heterogeneity of a polymer sample with respect tomolecular weight. The greater the value of PDI, the greater theheterogeneity or "broadness" of molecular weight distribution. A trulymonodispersed system has, by definition, a PDI of 1.0. The closer thePDI of a given polymer approaches the theoretical limiting value of 1.0,the narrower is its molecular weight distribution.

As can be seen from the above equations, the z average molecular weightemphasizes the highest molecular weight fraction of the polymericsample. Accordingly, those resins having relatively low z averagemolecular weights are believed to exhibit better overall formulatedperformance characteristics.

Average molecular weight and molecular weight distribution data istypically determined by gel permeation chromatography (GPC). Thistechnique, in combination with calculations made against the retentiontimes determined for a series of primary molecular weight standards,affords a means of determining all of the aforementioned averagemolecular weights.

The thermal polymerization of dicyclopentadiene (DCPD) and modified DCPDmonomer streams is commonly practiced. These resins find wide utility inthe preparation of inks, adhesives and coatings, but their relativelylow overall performance excludes their use in the high performanceapplications. A principal motivation for using DCPD resins is low costand availability. Their limitation, for many applications, is that inspite of the use of modifiers, the resulting resins still contain asignificant proportion of high molecular weight polymer. This highmolecular weight fraction limits solubility and compatibility andultimately the utility of the resins. These resins also typically havedark colors.

Limited solubility and compatibility severely restricts the use of theexisting thermally polymerized DCPD-based resins in many potentialapplications. Substantial concentrations of olefinic, vinyl aromatic orother reactive modifiers, when used in combination with shortpolymerization times, limits the proportion of undesirable highmolecular weight material in a resin. However the inherent disadvantageof this approach is that it gives low resin yields. U. S. Pat. No.4,650,829 discloses such a short reaction time and low reactiontemperature polymerization of dilute DCPD streams. While it does affordthe desired low molecular weight resins, it would be expected to givelow yields. Another major disadvantage to using DCPD, and in particularthe commercially available DCPD streams, which can contain significantproportions of the vinyl aromatics modifiers, is that they give darkcolored resins. Resins having Gardner colors of greater than about 7 aregenerally unacceptable for adhesive and coating applications. U.S. Pat.No. 5,171,793 also discloses conditions where short polymerizationtimes, in combination with high concentrations of reactive modifiers,result in resins with desirable molecular weights, but unfortunately theyields are low and the final resins have very dark colors. The resins ofthis patent generally have Gardner 16 colors and require hydrogenationprocesses to produce the light colors required for adhesives.

The present invention provides a method for preparing resins havingrelatively low molecular weights and relatively narrow molecular weightdistributions. The invention also provides a method for preparing resinshaving light colors acceptable for use in a wide range of adhesiveapplications. Furthermore, the invention provides resins which exhibitgood performance in hot-melt and pressure sensitive adhesives. Theinvention further provides improved resins for pigment flushingapplications and lithographic gel varnish printing ink applications.

SUMMARY OF THE INVENTION

In general, the present invention relates to a method for producing athermally polymerized dicyclopentadiene resin which comprises heating areaction material including a cyclopentadiene and/or dicyclopentadiene(DCPD) monomer, preferably under autogenous pressure, at a temperaturein the range of from about 240° C. to about 320° C. in the presence ofone or more strong acids, alone or in combination with olefinicmodifiers, for a time sufficient to produce a dicyclopentadiene oligomerresin which exhibits a weight average molecular weight in the range offrom about 260 to about 1000 and a polydispersity index of less thanabout 2.3. In the preferred method, organic sulfur compounds are alsopresent in the reaction material for molecular weight control. Theinvention may be practiced in either a continuous or batch reaction modeand with or without inert diluent being present. The reaction times mayrange from about 1 to about 40 hours, preferably from about 4 to about20 hours.

After the high temperature polymerization reaction is complete, thecrude reaction product is worked up. The work-up consists of standardphysical distillation and stripping operations at temperatures designedto be significantly below the reaction temperature. The objective of thestripping operation is to remove inert solvent, unreacted monomer,modifiers and reaction product oils.

Commercial DCPD fractions for use in the invention are available frompetroleum refining exhibiting a purity from 40% to essentially puremonomer. In the practice of the invention olefinic material, present asmono-olefins, di-olefins, vinylaromatics, co-dimers, and others, arebelieved to act synergistically with a strong acid as a molecular weightmodifier producing polymers of dicyclopentadiene of very lowpolydispersity indexes. These olefins can be introduced either bycarefully selecting one of the less pure commercially available DCPDproducts and/or by intentionally blending DCPD with the olefinicmodifiers to prepare the polymerization feed stream.

Strong mineral acids and/or strong organic acids may be added in therange of from about 0.05 wt. % to about 0.5 wt. %. Hypophosphorous acidis the preferred acid for use in the invention as it has been observedto yield very light resins exhibiting. improved molecular weightcharacteristics.

The organic sulfur compounds are typically added in the range of 0.1 wt.% to 0.5 wt. %. In a typical use of the present invention, the organicsulfur compound may be selected from the group consisting of isopropylmercaptan, thiophenol, thiosalicylic acid, 2,6-tert-butylphenol-4-thiol,phenyldisulfide, nonylphenol disulfide oligomer,di-(3,5-tert-butylphen-3-ol)disulfide, thiobis-β-naphthol,tetramethylthiuram disulfide, a mixture of3,5-tert-butylphen-3-olsulfide, di-(3,5-tert-butylphen-3-ol)disulfide,di-(3,5-tert-butylphen-3-ol)trisulfide, anddi-(3,5-tert-butylphen-3-ol)tetrasulfide and mixtures of those organicsulfides.

Final resin colors for the dicyclopentadiene oligomers of the inventionadvantageously lie in the range of from about 3 to 7, rendering theresins useful in a wide range of applications without the need forfurther processing to achieve a desired final color.

The relatively narrow molecular weight distribution and light finalcolor of the resins of the present invention are of significant benefitin adhesive, ink, coating and related applications. In particular, theinvention is useful in the formulation of hot-melt and pressuresensitive adhesives, as well as pigment flushing and gelled inkvarnishes.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention will now be described in furtherdetail in the following specification in conjunction with theaccompanying drawings in which:

FIG. 1 is a graphical illustration which shows gel permeationchromatography (GPC) traces for dicyclopentadiene resins preparedaccording to the present invention using a strong acid during thethermal polymerization of the dicyclopentadiene with an olefinic monomeror mixture of monomers (FIG. 1A and FIG. 1B), and for adicyclopentadiene resin prepared without a strong acid during thethermal polymerization of the dicyclopentadiene with an olefinic monomer(FIG. 1C); and

FIG. 2 is a graphical illustration which shows gel permeationchromatography (CPC) traces for a dicyclopentadiene resin preparedaccording to the present invention using a mineral acid during thethermal polymerization of dicyclopentadiene with piperylene and styrene(FIG. 2A), and for a dicyclopentadiene resin prepared according to thepresent invention using a strong acid and an organic sulfide during thethermal polymerization of the dicyclopentadiene with piperylene andstyrene (FIG. 2B and 2C).

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the preparation of light colored,narrow molecular weight range resins by a process which involves thethermal polymerization of dicyclopentadiene monomer. Most advantageouslydicyclopentadiene monomer, containing olefinic modifiers in combinationwith strong acid and optionally organic sulfur compounds is used. Thestrong acid way be present at relatively low concentrations (typicallyfrom about 0,025 wt. % to about 0.6 wt. %, but not limited to thesevalues). The strong acid is preferably selected from the groupconsisting of hypophosphorous acid, para-toluenesulfonic acid,methanesulfonic acid, hydrochloric acid, iodine, phosphoric acid andsulfuric acid. Without being bound by theory, it is believed that theiodine acts as hydroiodic acid (HI). It is believed that any BronstedAcid may be used in the present invention. A Bronsted Acid is an acidcapable of giving up protons. As used herein, the term "strong" inreference to the acidic component indicates a relatively strong protondonor.

Although each of these acids are effectively used alone in the thermalpolymerization process, mixtures of the acids are also suitable forpreparing DCPD resins having both good color and good molecular weightcharacteristics. For example, a mixture of hypophosphorous acid (at aconcentration of about 0.1 wt. %) and para-toluenesulfonic acid (at aconcentration of about 0.05 wt. %) may be used to prepare a resin ofDCPD, piperylene and styrene. (See FIG. 2A).

At concentrations below about 0.025%, the strong acid may be lesseffective at controlling the resin's molecular weight distribution,although the effect can only be completely diminished if no strong acidis present. At concentrations above about 1.0%, there may be littleadditional improvement in the product's molecular weight or molecularweight distribution.

In end use formulations or other situations where a trace of residualstrong acid may not be acceptable, the residual strong acid in the resinmay be removed by neutralization with a suitable base. The neutralizedresin may be filtered or otherwise treated to remove the trace of saltformed by the neutralization.

In accordance with one embodiment of the present invention, an organicsulfur compound may be used in combination with the strong acid tofurther improve the molecular weight characteristics of thepolymerization product. Effective organic sulfur compounds which may beused include substituted phenol polysulfides, aliphatic mercaptans,aromatic mercaptans and aliphatic/aromatic or mixed sulfides, but thislisting is illustrative only and other organic sulfur compounds may befound to be useful in the invention. Commercially available andpreferred species include the phenolic poly-or disulfide products soldunder the trade names ETHANOX 323 (Ethyl Corporation), VULTAC 2(Pennwalt) and SANTOWHITE CRYSTALS (Monsanto).

It is preferred that the starting material of the present inventioncontain a minimum of 40 wt. % dicyclopentadiene (DCPD) monomer.Inexpensive commercially available DCPD concentrates typically rangefrom 50 wt. % to 90 wt. % DCPD and therefore are most preferred,although the very high purity DCPD blended with olefinic modifiersfunctions well. To generate the lightest final resin color, it ispreferred that the DCPD stream be substantially clear, bright andcolorless. Dark colored streams do not generally afford light finalresin colors, but the molecular weight controlling effect of the presentinvention is not generally affected by starting material's initialcolor. Hydrogenation may be used to decolorize dark final resin color,but a distinct advantage of the invention is that the need forhydrogenation is greatly curtailed or eliminated.

The method of the present invention is effective for controlling themolecular weight distribution of the resin from pure DCPD monomer or forresin made from DCPD containing up to about 40 wt. % of olefinicmodifiers (based on reactive content). The olefinic modifier may benaturally present as it is in certain commercial DCPD fractions and/orby preparing blends.

In the present invention, it is preferred that the olefin modifier, ifused, be selected from the group consisting of ethylene, propylene,1-butene, isobutylene, butadiene, 1-pentene, 1-hexene,2-methyl-2-butene, isoprene, 1,3-pentadiene (piperylene), 1-octene,limonene, α-pinene, β-pinene, styrene, vinyl toluene, α-methyl styrene,indene, methyl methacrylate, acrylic acid or mixtures of those olefins,but other olefins may be used. An olefinic modifier is defined to be anymaterial containing one or more carbon to carbon double bonds. Thisdefinition only excludes dicyclopentadiene monomer itself.

Because of their lower cost, the preferred olefinic modifiers arefrequently those which occur naturally in some commercially availableDCPD products. In the terms of modifier performance it must beemphasized that those modifiers added intentionally, such as ethylene,propylene, piperylene, styrene etc., are completely acceptable and insome ways they can afford better modification.

It is believed that the presence of a strong acid together with anolefinic compound contributes to a synergistic effect in producing thenarrow range low molecular weight DCPD oligomers of the invention.

The thermal reaction process for the polymerization of DCPD or mixedDCPD streams has been thoroughly described in the patent literature andit is routinely practiced by several manufactures. Typical batchpolymerizations, as described in U.S. Pat. No. 4,010,130, aremechanically entirely suitable to practice the present invention. Thechemistry of the present invention is believed to be relativelyindependent of the mode of polymerization and may therefore be practicedin either batch or continuous reaction process, both with or withoutinert diluent being present.

The reaction temperature may generally range from about 240° C. to about320° C., but most preferably it should be in the range of from about250° C. to about 270° C. The residence time at reaction temperature maybe up to about 40 hours, but most preferably it is from about 4 hours toabout 20 hours.

Isolating the resins of the present invention from the crude reactionproduct involves techniques and physical distillation and strippingprocesses which are well known to those skilled in the art. Normally, bydesign the work-up temperature is significantly lower than the reactiontemperature (normally at least 20° C. lower).

The molecular weight distribution of the preferred resins, as defined bypolydispersity index (PDI), is typically less than 2.4. Preferred resinsproduced according to the invention exhibit PDI values less than 2.0.

The resins of the present invention are characterized generally asoligomers of dicyclopentadiene, having a weight average molecular weightof less than about 1000 and a polydispersity index which is preferablyless than about 2.3. Thus, the structure of the polymer may contain lessthan about 8 dicyclopentadiene units, and at the preferred weightaverage molecular weight range of from about 250 to about 700 may havefrom 2 to 6 dicyclopentadiene units. It will be appreciated that resinsproduced according to the present invention advantageously exhibit M_(w)values of less than about 700, whereas resins prepared without the useof mineral acids in the thermal polymerization of dicyclopentadieneexhibit M_(w) values greater than about 1000. The M_(z) value for theresins of the present invention are typically less than 1,500. Bycomparison, the M_(z) value for control resins prepared without a strongacid and/or organic sulfur species are of the order of 2,500.

In the embodiments of the invention which involve polymerization ofdicyclopentadiene along with an olefinic compound, the olefinic compoundis believed to enter into the chain of pentadiene units so that thetotal weight average molecular weight remains below about 1000 and avery narrow spread of molecular weights is achieved. It is believed thatthe strong acid and, if used, the organic sulfur compound, actcatalytically in the formation of the oligomer to limit the weightaverage molecular weight and to control the polydispersity of theresulting material.

There are many types of adhesives used commercially, including waterborne, solvent borne, reactive and hot-melt types. The resins of thepresent invention are believed to be useful in all of these basicsystems. The type of adhesive chosen for a particular application isdependent on the requirements of the application. The examples providedhere involve two of the largest general types, "hot-melt" and "pressuresensitive" adhesives.

Hot-melt adhesives are generally composed of ethylene and ethylenicallyunsaturated ester based elastomers, formulated with one or more resins(tackifiers), waxes and/or oils. Examples of the elastomers used in thepresent examples include ethylene-vinyl acetate (EVA) copolymers andethylene-acrylate copolymers. Obviously a multitude of differentformulated adhesives can be based on the same general components.Commercially, the ethylene-vinyl acetate polymers have extensiveutility. With these amorphous elastomers, the wax is present to bothcontrol molten adhesive viscosity, for ease of handling, as well as toallow the adhesive to set once it cools. The wax crystallizes and thecrystals act to physically reinforce and set the adhesive bond.

Existing standard tackifiers embody a range of resins including all ofthose resins that are available from the rosin ester, hydrocarbon resinand terpene resin families. The conventional thermal hydrocarbon resinsand its technology is included within the above families but they haverelatively poor polymer compatibility and therefore they are limited touse in low performance adhesive application.

Pressure sensitive adhesives are typically comprised of blends thatinclude polymer, tackifier resin and optionally, mineral oil components.The polymer may include any of a number of different types ofelastomers, but frequently involves a block copolymer thermoplasticelastomer. Typically these block copolymers are composed ofhomopolystyrene "blocks" or segments, A, and a hydrocarbon segment, B,resulting in an A-B-A block structure. The styrene content may vary aswell as the hydrocarbon segment placement. Typically the hydrocarbonsegment is derived from isoprene, butadiene, hydrogenated butadiene orcombinations of these or other hydrocarbon monomers. They can, inaddition to the traditional linear configuration as previouslydescribed, have branched or radial configurations. Again there is amyriad of different products commercially available and their specificuses are highly dependent on the application requirements.

Oil may be used to plasticize the adhesive system. Generally speaking,the plasticizing process lowers the system's glass transitiontemperature (T_(g)) and reduces the strength properties of the polymer.The tackifier resin component is typically from the very general groupconsisting of hydrocarbon resin, terpene resin or rosin ester. The resinaffords the tack properties needed for the bond formation process. Theresin component must typically have good compatibility in order togenerate the desired adhesive and cohesive properties.

The present invention provides resins which are highly compatible withethylene-unsaturated ester copolymers used for hot melt adhesives andwhich exhibit utility in block copolymer derived pressure sensitiveadhesive applications.

Printing inks, in a very general sense, are combinations of pigment,binder and solvent. The binder serves to provide toughness and adherethe pigment to the substrate surface. The solvent serves as a means ofapplying the pigment, and the ink drys when solvent either evaporates,oxidizes and/or penetrates into the substrate.

Lithographic printing is one of the three most commonly used printingprocesses. For lithographic printing a high boiling aliphatic and/or afatty acid derived ester solvent is often used. Compatibility of thebinder resin system with the solvent is an important performancerequirement.

The pigment may be introduced into a lithographic ink by eitherdispersing dry pigment into the binder/solvent mixture by means of highshear mixing, or by the preferred means of pigment "flushing". Inkpigments are synthesized by techniques that ultimately result in ahydrated pigment mass termed "press-cake." Flushing involves displacingthe water by intensive mixing in the presence of a varnish typicallyconsisting of a high solubility resin and ink solvent. This in effect"flushes" the water from the pigment resulting in a pigment dispersionin varnish.

Commercial lithographic printing inks are typically constructed from agelled varnish and the flushed pigment dispersion. In order to achieveacceptable performance on the printing press, the ink system must havecertain rheological characteristics. The desired rheologicalcharacteristics are imparted by the gelled varnish. The gelled varnishrheological characteristics are often achieved by the addition ofaluminum-based gelling agents which react with the resins of the varnishsystems.

The gellable lithographic varnishes are typically composed of severalresins, often a high molecular weight resin and a low molecular weightresin. The high molecular weight polymer is the species desired to reactwith the gelling agent to achieve the proper rheology. The low molecularweight resin is used to "solubilize" the system so that a homogeneousmixture results. Typically the low molecular weight resin interfereswith the formation of the proper theology by dilution, and therefore hasa dilatory effect.

The present invention provides resins having good utility for pigmentflushing and more specifically resins which provide improved finalprinted ink gloss. Resins according to the invention exhibitexceptionally good solubility properties in ink formulations andexceptionally good varnish gel reactivity.

Thus, the commercial uses for resins produced according to the presentinvention include, but are not limited to, adhesive, ink and varnishformulations. For example, the resins of the invention may also be usedas "green tack" promoters in rubber processing for improving theproperties and handling characteristics of the material prior tovulcanization.

The invention will now be further described with reference to thefollowing examples which are intended to illustrate, but not to limit,the invention.

EXAMPLE I

An autoclave reactor equipped with external heating, cooling, agitationand pressure capabilities was charged with 1075 grams DCPD concentrate(83 wt. % DCPD by weight, 15 wt. % codimers), 375 grams of piperyleneconcentrate (70 wt. % cis and trans 1, 3 pentadiene by weight), 75 gramsof styrene, 3 grams of hypophosphorous acid (50% aqueous solution) and0.75 grams of para-toluenesulfonic acid.

The autoclave was sealed and heated to 265° C. over a 1 hour period oftime. Once the 265° C. temperature was reached, the autoclave was cooledas necessary to maintain a temperature of 265° C. for a period of 4hours. The autoclave was then cooled to 120° C. and the reaction productdischarged, under an inert atmosphere, for work-up. The reaction productwas a pale yellow viscous semi-solid.

A 1375 gram sample of the reaction product was transferred to athree-neck round bottom flask which was equipped with a nitrogeninlet/thermometer adaptor, an agitator assembly, a steam sparge line anda take-off/condenser system. The reaction product was slowly heated to240° C. under a nitrogen blanket. Once the 240° C. temperature wasreached, the reaction product was steam sparged to remove residualmonomer and reaction oils. The sparging was continued until the resinsoftening point of about 100° C. was reached. The finished resin wascooled to 180° C. and discharged into an appropriate container.

The final resin had the following properties:

    ______________________________________                                        Softening Point, R&B    99° C.                                         Gardner Color, Neat     5+                                                    Resin Yield, %          83%                                                   Molecular Weight.sup.1                                                          M.sub.n               339                                                     M.sub.w               620                                                     M.sub.z               1387                                                    PDI                   1.8                                                   Cloud Point.sup.2       73° C.                                         ______________________________________                                         .sup.1 Molecular Weights by GPC                                               .sup.2 2:2:1 EVA ELVAX 250/Microcrystalline Wax/Resin                    

EXAMPLE II Comparison Example

The same proportion of starting materials as used in EXAMPLE I with theexclusion of the strong acids were charged into an autoclave and reactedas per EXAMPLE I. The reaction product was sparged to the desired 100°C. softening point using the method of EXAMPLE I.

The finished comparison resin had the following properties:

    ______________________________________                                        Softening Point, R&B    99° C.                                         Gardner Color, Neat     8+                                                    Resin Yield, %          87%                                                   Molecular Weight                                                                M.sub.n               427                                                     M.sub.w               1028                                                    M.sub.z               2515                                                    PDI                   2.4                                                   Cloud Point             100° C.                                        ______________________________________                                    

The resin produced without the strong acid was much darker, 3 Gardnercolor numbers, than the resin produced according to the method of thepresent invention. The cloud point, as a relative measure ofcompatibility, of the resin of EXAMPLE I indicates improvedcompatibility relative to the resin of comparative EXAMPLE II. The resinof EXAMPLE I resulted in a final resin M_(w) and M_(z) of 620 and 1389,respectively, versus 1028 and 2515, respectively, for the resin ofcomparative EXAMPLE II. Thus, the present invention affords a means ofimproving color and molecular weight distribution relative to a resinpreparation of the previous art.

EXAMPLES III-XV

A series of thermally polymerized dicyclopentadiene resins were preparedwith varying amount of DCPD, olefinic monomer(s), strong acid(s) andoptionally organic sulfur containing species. The amounts of thereaction materials are given in TABLES I and II. The reaction conditionswere similar to the conditions of EXAMPLES I and II. The reactionconditions and yields are given in TABLES III and IV. After the initialreaction, the reaction mixture was stripped with a nitrogen sparge at230° C. The characteristics of the final resin are given in TABLES V andVI.

                                      TABLE I                                     __________________________________________________________________________    Example                                                                             III  IV  V    VI  VII  VIII                                                                              IX                                           __________________________________________________________________________    MW Control                                                                          0.10%                                                                              0.10%                                                                             0.10%                                                                              0.10%                                                                             0.05%                                                                              0.10%                                                                             0.05%                                        Package                                                                             Hypo A                                                                             Hypo A                                                                            Hypo A                                                                             Hypo A                                                                            PTSA Hypo A                                                                            Hypo A                                             0.05%                                                                              0.05%                                                                             0.05%                                                                              0.05%                                                                             0.3% 0.05%                                                                             0.05%                                              PTSA PTSA                                                                              PTSA PTSA                                                                              E-323                                                                              PTSA                                                                              PTSA                                                    0.3%     0.3%     0.3%                                                                              0.3%                                                    E-323                                                                             E-323                                                                              E-323    E-323                                                                             E-323                                        Monomer                                                                       DCPD                                                                          B     95.3 75.0                                                                              80.0 70.0                                                                              77.5 77.5                                                                              77.5                                         C                                                                             Modifier                                                                      Piperylene 10.0                                                                              5.0  30.0                                                                              22.5 22.5                                                                              22.5                                         Styrene        15.0                                                           Propylene                                                                           3.0                                                                     Ethylene                                                                            1.7                                                                     1-Octene   15.0                                                               Hypo A = Hypophosphorous Acid                                                 E-323 = ETHANOX 323 (Ethyl Corporation)                                       PTSA = para-Toluenesulfonic acid                                              DCPD A = ˜95% DCPD, 5% codimers                                         DCPD B = ˜83% DCPD, 15% codimers (modifier)                             DCPD C = ˜60% DCPD, 15% codimers, 12% Vinyl Aromatic                    __________________________________________________________________________

                  TABLE II                                                        ______________________________________                                        Examples X       XI      XII   XIII  XIV   XV                                 ______________________________________                                        MW Control                                                                             0.2%    0.1%    0.1%  0.1%  0.1%  0.05%                              Package  Hypo A  Hypo A  Hypo A                                                                              Hypo A                                                                              Hypo A                                                                              Hypo A                                      0.05%   0.05%   0.05% 0.05% 0.05% 0.05%                                       PTSA    PTSA    PTSA  PTSA  Iodine                                                                              PTSA                                        0.3%    0.3%    0.3%  0.3%  0.3%  0.3%                                        E-323           0-M   E-323 E-323 E-323                              Monomer:                                                                      DCPD                                                                          A        65.0                                                                 B                75.0    70.0  70.0  70.0  70.0                               Piperylene                                                                             30.0            25.0  25.0  25.0  15.0                               Styrene  5.0             5.0   5.0   5.0   15.0                               1-Octene         25.0                                                         Hypo A = Hypophosphorous Acid                                                 E-323 = ETHANOX 323 (Ethyl Corporation)                                       PTSA = para-Toluenesulfonic acid                                              DCPD A = ˜95% DCPD, 5% codimers                                         DCPD B = ˜83% DCPD, 15% codimers (modifier)                             DCPD C = ˜60% DCPD, 15% codimers, 12% Vinyl Aromatic                    0-M = Octylmercaptan                                                          ______________________________________                                    

                  TABLE III                                                       ______________________________________                                        Examples   III    IV     V    VI   VII   VIII IX                              ______________________________________                                        Reaction   265    265    265  265  265   265  250                             Temperature (°C.)                                                      Reaction   3      6      5    8    6     6    20                              Time (hours)                                                                  Gardner Color                                                                            6-     4-     5+   4+   5+    4    3-                              (Base Resin, Neat)                 (Green                                                                        Hue)                                       Reaction   89     78     89   78   81    84   84                              Yield (%)                                                                     ______________________________________                                    

                  TABLE IV                                                        ______________________________________                                        Examples    X      XI      XII  XIII  XIV  XV                                 ______________________________________                                        Reaction    265    265     265  265   265  265                                Temperature (°C.)                                                      Reaction    4      4       6    6     6    6                                  Time (hours)                                                                  Gardner Color                                                                             5-     5+      5-   4+    4-   4+                                 (Base Resin, Neat)                                                            Reaction                                                                      Yield (%)   81     77      81   79    80   87                                 ______________________________________                                    

                  TABLE V                                                         ______________________________________                                        Stripped Resin, Nitrogen Sparge at 230° C.                             Examples   III    IV     V    VI   VII   VIII IX                              ______________________________________                                        Gardner    6-     5-     7-   5    6+    5    3                               Color, Neat                        (Green)                                    S.P. (R&B) 124    90.5   142  101  129   123  125                             Molecular                                                                     Weight Data                                                                     M.sub.n  --     360    --   300  --    358  --                                M.sub.w  --     550    --   513  --    628  --                                M.sub.z  --     920    --   998  --    1190 --                                PDI      --     1.5    --   1.7  --    1.7  --                              ______________________________________                                    

                  TABLE VI                                                        ______________________________________                                        Stripped Resin, Nitrogen Sparge at 230° C.                             Examples    X      XI      XII  XIII  XIV   XV                                ______________________________________                                        Gardner     6-     6       5+   5     4+    5                                 Color, Neat                                                                   S.P. (°C.)                                                                         100    83      104  102   102   103                               Molecular                                                                     Weight Data                                                                     M.sub.n   --     427     --   337   341   --                                  M.sub.w   --     640     --   578   554   --                                  M.sub.z   --     1052    --   1047  1021  --                                  PDI       --     1.5     --   1.7   1.6   --                                2:2:1                           73°                                                                          72° C.                           EVA/Wax/Resin                                                                 Cloud Point                                                                   ______________________________________                                    

EXAMPLES III-XV were representative of the preparation of adicyclopentadiene resin according to the present invention from lightcolored DCPD streams. The resulting resins had final colors of from 3 to7 with weight average molecular weights ranging from 513 to 640. TheM_(w) /M_(n) ratio varied from 1.5 to 1.7. Thus, the resins preparedaccording to the present invention had relatively narrow molecularweight distributions, relatively low molecular weights, and relativelylight colors.

EXAMPLES XVI-XX

A series of reaction examples are presented in TABLE VII that wereprepared from a crude dicyclopentadiene concentrate polymerizedsubstantially in the manner of EXAMPLE I. The reaction results/physicalproperties are presented in TABLES VIII and IX. These examples furtherillustrate that the mechanism of the present invention is independent ofthe source of DCPD. The crude dicyclopentadiene feed containsapproximately 60% DCPD by weight at approximately 92% total reactives.This material is amber/green, approximating a Gardner 5 color itself.

                  TABLE VII                                                       ______________________________________                                                Comparison                                                            Examples                                                                              XVI      XVII     XVIII  XIX    XX                                    ______________________________________                                        Mw Control                                                                            None     0.25%    0.25%  0.2%   0.2%                                  Package          Iodine   Iodine H.sub.3 PO.sub.4                                                                     H.sub.3 PO.sub.2                      Monomer:                                                                        DCPD                                                                           A                                                                             B                                                                             C    100.0    100.0    75.0   75.0   75.0                                  alpha-Pinene              25.0   25.0   25.0                                  ______________________________________                                    

                  TABLE VIII                                                      ______________________________________                                        Examples     XVI     XVII    XVIII XIX  XX                                    ______________________________________                                        Reaction     265     265     265   265  265                                   Temperature (°C.)                                                      Reaction     4       4       4     4    4                                     Time (hours)                                                                  Gardner Color                                                                              --      --      --    --   --                                    (Base Resin, Neat)                                                            Reaction     85      81      60    65   63                                    Yield (%)                                                                     ______________________________________                                    

                  TABLE IX                                                        ______________________________________                                        Stripped Resin, Nitrogen Sparge at 230° C.                             Examples   XVI     XVII     XVIII XIX   XX                                    ______________________________________                                        Gardner    12+     18+      18+   18+   11-                                   Color, Neat                                                                   S.P. (°C.)                                                                        109     109      94    101   102                                   Molecular                                                                     Weight Data                                                                     M.sub.n  355     314      339   --    --                                      M.sub.w  982     563      478   --    --                                      M.sub.z  4207    1223     761   --    --                                      PDI      2.8     1.8      1.4   --    --                                    ______________________________________                                         H.sub.3 PO.sub.4 = Phosphoric Acid                                       

Comparison EXAMPLE XVI is presented as a control. EXAMPLES XVII, XVIII,XIX and XX involve the addition of the strong acid of the presentinvention. EXAMPLE XVII illustrates that the use of a hydroiodic acid inaccordance with the present invention results in substantially improvedmolecular weight characteristics as indicated by the significantreduction in the weight average molecular weight and the polydispersityindex.

EXAMPLES XVIII, XIX and XX illustrate that the copolymerized system ofDCPD concentrate and alpha-pinene results in a very narrow molecularweight as indicated by the 1.4 polydispersity index.

EXAMPLE XX further illustrates that, in addition to the molecular weightcontrolling feature of the present invention, the color of the finalproduct can be substantially improved by the presence of hypophosphorousacid.

EXAMPLES XXI-XXIV

A series of pressure sensitive adhesives were prepared by combining 25wt. % of a styrene-isoprene-styrene copolymer thermoplastic elastomer(SOL T 193B, Enichem Corp.) 20 wt. % and 55 wt. % of a resin. In EXAMPLEXXI, the resin was a catalytically polymerized, 95° C. softening point,"C5" hydrocarbon resin (WINGTACK 95, Goodyear Tire and Rubber Co.); inEXAMPLE XXII, the resin was a 100° C. softening pointrosin-pentaerythritol ester (SYLVATAC 2100, Arizona Chemical Co.); inEXAMPLE XXIII, the resin was the resin of EXAMPLE VI, and in EXAMPLEXXIV the resin was the resin of EXAMPLE IV.

The adhesives were coated onto a MYLAR (E. I. DuPont de Nemours & Co.)film and tested for tack, 180° peel, shear adhesion failure temperatureand 25° C. shear. The results of the tests are shown in TABLE X.

                  TABLE X                                                         ______________________________________                                        Example XXI        XXII      XXIII   XXIV                                     Resin   WINGTACK   SYLVATAC  Example Example                                          95         2100      VI      IV                                       Film    1.1        1.2       1.2     1.3                                      Thickness                                                                     (mils)                                                                        Polyken 1485 ± 163                                                                            1226 ± 255                                                                           1219 ± 149                                                                         1224 ± 125                            Probe Tack                                                                    (grams)                                                                       180° C.                                                                        5.98 ± .54                                                                            7.48 ± .17                                                                           6.57 ± .04                                                                         5.67 ± .20                            Peel (lbs/in)                                                                 Shear Ad-                                                                             65.6       60.0      61.7    63.9                                     hesion                                                                        Failure                                                                       Temp. (°C.)                                                            25° C. Shear                                                                   >10,0O0    >10,000   >10,000 >10,000                                  (min.)                                                                        ______________________________________                                    

The adhesives prepared from the resins of the present invention(EXAMPLES XXIII and XXIV) performed as well as the adhesives preparedfrom resins of accepted chemistry. Thus the resins of the presentinvention are substantially suitable for the production of pressuresensitive adhesives. However, it will be appreciated that resinsaccording to the invention may be produced more economically thanconventional resins of this type with improved color and molecularweight characteristics.

EXAMPLES XXV-XXVII

A series of EVA based hot-melts adhesives were prepared and aresummarized in TABLE XI. The systems were derived from 20 wt. % EVA I(ELVAX 260, E. I. DuPont de Nemours & Co.), 10 wt. % EVA 2 (ELVAX 410,E. I. DuPont de Nemours & Co.), 30 wt. % Wax (SHELLWAX 300, ShellChemical Co.) and 40 wt. % resin. In Comparative EXAMPLE XXV, the resinis a commercially available catalytically polymerized aliphatichydrocarbon resin (STA-TAC B, Arizona Chemical Co.). In EXAMPLE XXVI theresin is the resin from EXAMPLE VI and in EXAMPLE XXVII the resin is theresin from EXAMPLE XV. The systems were melt blended at 175° C. for 2.5hours under a nitrogen blanket.

The cloud point results indicate greater system compatibility from theresins of the present invention. The resins of the present inventionalso result in desirably light hot-melt color.

                  TABLE XI                                                        ______________________________________                                        Example       XXV        XXVI      XXVII                                      ______________________________________                                        Resin         STA-TAC    Example   Example                                                  B          VI        XV                                         Resin         100        101       103                                        Softening Point                                                               (°C.)                                                                  Neat Resin Color                                                                            6          5-        5                                          Hot-Melt Color                                                                              5          3         3                                          Viscosity (cps)                                                                             3850       3980      4500                                       @ 175° C.                                                              Cloud Point (°C.)                                                                    112        63        63                                         Yield         --         652       675                                        (lbs./inch)                                                                   ______________________________________                                    

EXAMPLES XXVIII-XXX

Several pigment flushing varnishes were prepared by dissolving 60 wt. %resin in 40 wt. % of an aliphatic ink solvent (MAGIESOL 47, MagieBrother Chemical Company/Pennzoil) at elevated temperature. In EXAMPLEXXVIII, the resin was commercially available catalytically polymerized"C9" resin with a softening point of 140° C. (NEVCHEM 140, NevilleChemical Co.); in EXAMPLE XXIX, the resin was commercially availableDCPD based resin with a softening point of about 140° C. (BETAPRENE 255,Arizona Chemical Co.); and in EXAMPLE XXX, the resin was the resin ofEXAMPLE V with a softening point of 142° C. The physical properties ofthe resin varnishes are given in TABLE XII. The varnishes were evaluatedin a pigment flushing operation and in an ink/printing evaluation. Theprinting evaluation was conducted by blending 30 parts of the pigmentdispersion with 70 parts of a gel varnish. The results are also shown inTABLE XII.

                                      TABLE XII                                   __________________________________________________________________________    Pigment Flushing and Printing Evaluation                                      __________________________________________________________________________    Example          XXVIII XXIX    XXX                                           Comparative      "Cat. C9"                                                                            Modified                                                                              Example                                       Examples         Neville                                                                              DCPD    V                                                              NEVCHEM                                                                              Arizona                                                                140    BETAPRENE                                                                     255                                                   S.P. (°C.)                                                                              ˜140° C.                                                                ˜140° C.                                                                 142° C.                                ---------------------------------->                                           ---------------------------------->                                           (MAGIESOL 47 Aliphatic Ink Solvent)                                           Viscosity @      Z6.8   Z4.0    Z1.0                                          25° C.    191 secs                                                                             68 secs 28.5 secs                                     Pigment Flushing Operation:                                                   ----------------------------------->                                          (grams)                                                                       Flushed water    19.17  19.81   19.93                                         (grams)                                                                       ------------------------------->                                              Water Break      <---------------equal------------------>                     Ink/Printing Evaluation:                                                      30 parts Flush Color                                                          70 parts Gelled Varnish                                                       % Dil. to Tack   8.13   8.13    6.63                                          Ink Gloss        17.8   19.6    22.8                                          Print Density    1.72   1.95    1.98                                          Ink Misting      3-     3-      3-                                            Set-off (min.)   <1     1       1                                             Heatset Dry      1 pass 1 pass  1 pass                                        __________________________________________________________________________

The flushing varnish prepared with the resin of the present inventionhad an advantageously lower viscosity and performed substantially in themanner of the varnishes prepared with the commercially available resinsin the flushing operation. The lower solution viscosity afforded by theresin of the present invention is an advantage for ease of handling andmixing.

The print evaluation of ink prepared from the flushed pigment dispersionof the resin of the present invention afforded significantly improvedgloss relative to the commercially available products with substantiallyequal printing characteristics.

EXAMPLES XXXI-XXXII

Two lithographic gel varnishes were prepared by dissolving a highviscosity phenolic modified rosin resin (BECKACITE 6000, ArizonaChemical Co.), an alkyd, and a solubilizing resin in an aliphatic inksolvent (MAGIESOL 47, Magie Brothers Chem. Co.) at 175° C. The solutionwas then held at 175° C. and AIEM and OAO gelling agents (ChattemChemical Co.) added. The system was allowed to react at 175° C. for onehour. In EXAMPLE XXXI the solubilizing resin is a commercially availableDCPD based resin with a 140° C. softening point (BETAPRENE 255, ArizonaChemical Co.), and in EXAMPLE XXXII, the solubilizing resin is resinfrom EXAMPLE V with a softening point of 142° C. The theologicalproperties as determined on a Laray Viscometer are presented in TABLEXIII.

                  TABLE XIII                                                      ______________________________________                                        Gel Varnish Formulation                                                       ______________________________________                                        High Viscosity Modified Phenolic Resin (1)                                                             29.0   parts                                         Solubilizing Hydrocarbon Resin                                                                         20.0   parts                                         Alkyd                    15.0   parts                                         AIEM Solution (2)        1.0    parts                                         OAO Solution (3)         2.0    parts                                         MAGIESOL 47, Aliphatic Ink Solvent                                                                     33.0   parts                                                                  100.0                                                ______________________________________                                        Laray Viscometer                                                              Gel Rheology Evaluation                                                       ______________________________________                                        Example      XXXI            XXXII                                            Solubilizing Arizona Chemical                                                                              Example                                          Hydrocarbon  Modified DCPD Resin                                                                           V                                                Resin        BETAPRENE                                                                     255                                                              Viscosity (cps)                                                                            510             429                                              Yield Value  15725           26395                                            Shortness Ratio                                                                            30.6            61.5                                             Slope        1.56            1.86                                             M47 Tolerance                                                                              11 mls.         10 mls.                                          ______________________________________                                         (1) Beckacite 6000, Arizona Chemical Company                                  (2) AIEM: Chelated Alkoxide                                                   (3) OAO: Oxyaluminum Octoate                                             

The resin of EXAMPLE V affords significantly greater gel reactivity asindicated by the shortness ratio of EXAMPLE XXXII. Shortness ratio is ameasure of the relative elastic character of the varnish independent ofviscosity. The additional reactivity was achieved at substantially equalaliphatic solubility. Traditionally the solubilizing resin deleteriouslyeffected the gel reaction and therefore the exceptional gel strengthobserved with resin EXAMPLE V is a significant positive result.

Therefore, the present invention provides a method for preparingthermally polymerized resins of dicyclopentadiene which have improvedcompatibility and solubility characteristics. In addition, the formationof high molecular weight fractions are minimized as is the formation ofadditional color during the polymerization. Further, resins preparedaccording to the present invention are useful in preparing adhesives andink varnishes.

Having thus described various preferred embodiments of the invention andseveral of its benefits and advantages, it will be understood by thoseof ordinary skill that the foregoing description is merely for thepurpose of illustration and that numerous substitutions, rearrangementsand modifications may be made in the invention without departing fromthe scope and spirit of the appended claims.

What is claimed is:
 1. A dicyclopentadiene resin produced according to a thermal polymerization process which comprises heating a reaction material consisting essentially of a cyclopentadiene and/or dicyclopentadiene monomer, and optionally, a modifier selected from the group consisting of ethylene, propylene, 1-butene, isobutylene, butadiene, 1-pentene, 1-hexene, 2-methyl-2-butene, isoprene, 1,3-pentadiene, 1-octene, limonene, α-pinene, β-pinene, styrene, vinyl toluene, α-methyl styrene, indene and mixtures thereof, at a temperature in the range of from about 240° C. to about 320° C. in the presence of a Bronsted acid selected from the group consisting of hypophosphorous acid, p-toluenesulfonic acid, hydrochloric acid, hydroiodic acid, phosphoric acid methane sulfonic acid, and mixtures thereof for a time sufficient to produce a dicyclopentadiene oligomer resin exhibiting a weight average molecular weight ranging from about 260 to about 1000, a cloud point of less than about 100° C. and a saponification value of essentially
 0. 2. A dicyclopentadiene resin, said resin being produced according to a thermal polymerization process which comprises:(a) placing a starting material in a reaction vessel capable of being sealed and pressurized, the starting material consisting essentially of a dicyclopentadiene concentrate, optionally, a modifier selected from the group consisting of ethylene, propylene, 1-butene, isobutylene, butadiene, 1-pentene, 1-hexene, 2-methyl-2-butene, isoprene, 1,3-pentadiene, 1-octene, limonene, α-pinene, β-pinene, styrene, vinyl toluene, α-methyl styrene, indene and mixtures thereof, and a Bronsted acid selected from the group consisting of hypophosphorous acid, p-toluenesulfonic acid, hydrochloric acid, hydrochloric hydroiodic acid, phosphoric acid methane sulfonic acid, and mixtures thereof; (b) sealing the starting material within the reaction vessel; and (c) heating and maintaining the temperature of the starting material for a period of time sufficient to cause the dicyclopentadiene to thermally polymerize to form a reaction product comprising a dicyclopentadiene oligomer resin,wherein the weight average molecular weight of the polymeric resin is less than about 1000, the resin has a color ranging from about 3 to about 7 on the Gardner scale, a ring and ball softening point ranging from about 80° C. to about 180° C., a saponification number of essentially 0 and a cloud point of less than about 100° C.
 3. A dicyclopentadiene resin having a cloud point of less than about 100° C., said resin being produced according to a thermal polymerization process which comprises:(a) placing a starting material in a reaction vessel capable of being sealed and pressurized, the starting material consisting essentially of:(1) from about 60 wt. % to about 99 wt. % of a dicyclopentadiene concentrate, comprising from about 60 to about 100 wt. % dicyclopentadiene, (2) from about 0 wt. % to about 40 wt. % of a compound selected from the group consisting of ethylene, propylene, 1-butene, isobutylene, butadiene, 1-pentene, 1-hexene, 2-methyl-2-butene, isoprene, 1,3-pentadiene, 1-octene, limonene, α-pinene, β-pinene, styrene, vinyl toluene, α-methyl styrene, indene and mixtures thereof, and (3) from about 0.1 wt. % to about 0.6 wt. % of a Bronsted acid selected from the group consisting of hypophosphorous acid, p-toluenesulfonic acid, hydrochloric acid, hydroiodic acid, phosphoric acid methane sulfonic acid, and mixtures thereof; (b) sealing the starting material within the reaction vessel; (c) raising the temperature of the starting material to a temperature in a range of from about 240° C. to about 320° C. over a period in the range of from about 45 minutes to about 75 minutes; (d) maintaining the temperature of the starting material in a range of from about 240° C. to about 320° C. for a period of time in the range of from about 1 hour to about 40 hours, thereby forming a reaction product including a dicyclopentadiene oligomer resin; (e) decreasing the temperature of the reaction product to within a temperature in a range of from about 10° C. to about 50° C. below the temperature to which the starting material was(f) placing the a period of time; (f) placing the reaction product under an inert gas atmosphere; (g) transferring the reaction product from the vessel to a steam sparging means; and (h) sparging the reaction product with steam to a resin softening point in the range of from about 80° C. to about 180° C.,wherein the weight average molecular weight of the resin is less than about 1000, the z average molecular weight is less than about 2000, the resin has a color ranging from about 3 to about 7 on the Gardner scale, a saponification number of essentially 0 and a ring and ball softening point ranging from about 80° C. to about 180° C.
 4. The dicyclopentadiene resin according to claim 3 having a weight average molecular weight in the range of from about 260 to about
 1000. 5. A pressure sensitive adhesive comprising:an elastomer; a mineral oil; and a dicyclopentadiene resin according to claim 3 having a weight average molecular weight in the range of from about 260 to about
 1000. 6. The pressure sensitive adhesive of claim 5 wherein the elastomer is selected from the group consisting block copolymer thermoplastic elastomers and radial copolymer thermoplastic elastomers.
 7. The pressure sensitive adhesive of claim 5 wherein the elastomer is selected from the group consisting of styrene-butadiene-styrene block copolymer and styrene-isoprene-styrene block copolymer.
 8. The pressure sensitive adhesive of claim 5 wherein the elastomer comprises from about 15 wt. % to about 50 wt. % of the adhesive, the mineral oil comprises from about 0 wt. % to about 25 wt. % of the adhesive and the resin comprises from about 30 wt. % to about 75 wt. % of the adhesive.
 9. A hot melt adhesive comprising:an elastomer; a wax; and a dicyclopentadiene resin according to claim 3 having a weight average molecular weight in the range of from about 260 to about
 1000. 10. The hot melt adhesive of claim 9 wherein the elastomer is an ethylene/ethylenically unsaturated ester copolymer.
 11. The hot melt adhesive of claim 10 wherein the ester copolymer is an ethylene-vinyl acetate copolymer.
 12. The hot melt adhesive of claim 9 comprising from about 20 wt. % to about 50 wt. % of the elastomer, from about 10 wt. % to about 40 wt. % of the wax, and from about 30 wt. % to about 60 wt. % of the dicyclopentadiene oligomer resin.
 13. A pigment flushing varnish for use in the preparation of flushed pigment dispersions, the varnish comprising:a lithographic ink solvent; and a dicyclopentadiene resin according to claim 3 having a weight average molecular weight in the range of from about 260 to about
 1000. 14. The pigment flushing varnish of claim 13 wherein the lithographic ink solvent is selected from the group consisting of aliphatic hydrocarbon based solvents and fatty acid ester based solvents.
 15. The pigment flushing varnish of claim 13 wherein the lithographic ink solvent is present at a concentration of from about 30 wt. % to about 60 wt. % and the dicyclopentadiene oligomer resin is present at a concentration of from about 70 wt. % to about 40 wt. %.
 16. A gelled lithographic ink varnish for use in the preparation of lithographic inks, the varnish comprising:high molecular weight resin; a lithographic solvent; a gelling agent; and a dicyclopentadiene resin according to claim 3 having a weight average molecular weight in the range of from about 260 to about
 1000. 17. The gelled lithographic ink varnish of claim 16 wherein the gelling agent is an aluminum compound.
 18. The gelled lithographic ink varnish of claim 17 wherein the gelling agent is selected from the group consisting of aluminum diisopropoxide acetoacetic ester chelate and oxyaluminum octoate.
 19. The gelled lithographic ink varnish of claim 16 wherein the high molecular weight resin is selected from the group consisting of phenolic modified rosin resin, maleic modified rosin resin, and rosin modified hydrocarbon resin.
 20. The gelled lithographic ink varnish of claim 16 wherein the high molecular weight resin is present at a concentration of from about 20 wt. % to about 40 wt. %, the gelling agent is present at a concentration of from about 1 wt. % to about 5 wt. %, the lithographic solvent is present at a concentration in the range of between about 10 wt. % to about 50 wt. %, and the dicyclopentadiene oligomer resin is present in a concentration of between about 10 wt. % and about 40 wt. %.
 21. The gelled lithographic ink varnish of claim 16 wherein the varnish further comprises an alkyd.
 22. The gelled lithographic ink varnish of claim 21 wherein the high molecular weight resin is present at a concentration of from about 20 wt. % to about 40 wt. %, the gelling agent is present at a concentration of from about 1 wt. % to about 5 wt. %, the lithographic solvent is present at a concentration in the range of between about 10 wt. % to about 50 wt. %, the alkyd is present in a concentration of from about 5 wt. % to about 25 wt. %, and the dicyclopentadiene oligomer resin is present in a concentration of between about 10 wt. % and about 40 wt. %.
 23. A composition for use in an ink or adhesive comprising:an ink solvent or an elastomer; and a dicyclopentadiene resin according to claim 3 having a weight average molecular weight in the range of from about 260 to about 1000 and a polydispersity index of less than about 2.3. 